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Genes, evolution & development > Evolution > Flashcards

Evolution Flashcards

1
Q

Define evolution

A

Change in the inherited characteristics of biological populations over successive generations

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2
Q

What are the three conditions for natural selection?

A

Heritable characteristics
Variation between individuals

Differing fitness between individuals

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3
Q

What is a genetic change over time?

A

Change in allele frequency.

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4
Q

What does natural selection affect?

A

The phenotype.

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5
Q

What Is the evidence for evolution?

A

Fossils, imperfect designs, biogeography, molecular genetics, natural selection in action.

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6
Q

Describe the evidence from fossils.

A

Trilobites changed over 3m years.

Whales evolved from land mammals.

Tiktaalik was the missing link from fish to mammals.

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7
Q

What is the evidence from bad design?

A

Left recurrent laryngeal nerve is 1m long by looping around the aorta instead of going directly. Because the larynk evolved from branchial arch, adaption not design.

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8
Q

What us the evidence from biogeography?

A

The distribution of species globally.

Galapagos islands gave Darwin thr insight needed. It shows specific adaption.

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9
Q

What does natural selection explain the existence of?

A

Endemic species and convergent evolution.

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10
Q

Describe the evidence from molecular genetics.

A

Dna is now the sole and universal carrier of the genetic code, suggesting a common ancestor.

Universal code, all organisms use it.

Can track evolution by comparing genetic sequences or looking at proteins.

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11
Q

What is a molecular clock?

A

Uses fossil constraints and rates of molecular change to find when two species diverged.
Compared for proteins, cytochrome c gene.

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12
Q

Lactose intolerance stuff.

A

Several genotypes associated with disesting cow’s milk.
Tolerance highest in Europe.
Strong evidence of natural selection, could be neutral theory.

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13
Q

What is the theory of pansperma?

A

Amino acids found on comets that form spontaneously hit earth.

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14
Q

What were around before cells?

A

Protobionts - made of lipids. Could reproduce and metabolise. Lived in the sea.

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15
Q

What was necessary for life?

A

Cool temperature, gravity, water and radiation protection.

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16
Q

All the oxygen early life stuff.

A

Look it up.

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17
Q

What is a species?

A

A population of reproducing organisms that is isolated from other populations.

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18
Q

What is directional, disruptive and stabilising selection?

A

Graphs yo.

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19
Q

What is allopathic speciation?

A

Due to geographical isolation.

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20
Q

What is sympatric speciation?

A

With a population in one geographical region.

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21
Q

What is genetic drift?

A

The change in allele frequency in a population.

Large changes are unlikely in large populations, but drift has major changes on a small population.

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22
Q

Describe a bottleneck event.

A

A sharp reduction in the size of a population, reducing the variation in a gene pool.

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23
Q

What is fitness?

A

The relative probability of survival and reproduction for a given genotype.

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24
Q

Describe sickle cell anemia.

A

Homozygotes are anaemic, heterozygotes less likely to get malaria (ADVANTAGE).

Caused by glutamic acid being replaced by valine.

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25
Q

How are genes that are deleterious be passed down?

A

Linked closely to Advantageous genes.

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26
Q

What is a maladaptive gene?

A

Non productive.

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27
Q

What is runaway sexual selection?

A

Females choice of mate, males over compensate with good characteristic.

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28
Q

Describe prezygotic barriers

A

Premating: habitat, some won’t meet.
Behavioural, not some mating rituals.
Temporal, in season at different times.

Post mating:
Mechanical, different sex organs not compatible.
Gametes, egg doesn’t chemically attract spermatogenesis.

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29
Q

Describe post zygote barriers.

A

Hybrid viability, hybrid dies prematurely.

Hybrid fertility, offspring infertile due to chromosome number.

Hybrid breakdown, over generations it weakens and becomes less fertile.

30
Q

Describe the biological species concept.

A

A population is a specific niche.

Species being groups of potentialy interbreeding populations which are reproductively isolated.

The lack of interbreeding is the isolating mechanism.

31
Q

Define family alturism.

A

Behaviour of an animal that benefits another at it’s own expense.
Ants - problem for darwin.

32
Q

Define inclusive fitness.

A

Direct + indirect fitness.
Individual and relatives.
Bill Hamilton.

33
Q

What is Hamiltons rule?

A

rb>c

r - Degree of relatedness.
b - benefit of altruistic behaviour.

c - cost of being alturistic.

34
Q

How does alturism come about?

A

Unlikely due to a gene.

Responding to similar genotypic individuals.

35
Q

Describe haplodiploidy and it’s benefits.

A

Females diploid, males haploid.
Males can be produced without fertilisation, females require fertilisation. the ant is more closely related to its sister than its offspring. This has a high relatedness and alturism.
Queen has identical genotype to her worker sisters.

36
Q

What are sponges?

A

Animals with no:
Muscles, neurons, organs, tissues, symmetry and reproductive organs.

They are heterotrophs with specialised flagella to capture food and perform intracellular digestion.

37
Q

Describe desert succulent plants.

A

Fleshy stems that store water, small leaves reduce water loss.
Two different families - cacti/euphorbs.
Evidence for convergent adaptions to life in arid conditions.

38
Q

Describe placental and marsupial mammals.

A

Placental - long lasting lacenta and developed offspring.
Marsupials have a pouch and 2 vaginas.

Convergent adaptions.
No placental mammals in australia. marsupials in australia, both in america.

39
Q

What is convergent evolution?

A

Different animals have evolved similarly.

40
Q

What is the neutral theory?

A

The genetic code is redundant - some synonymous changes don’t change the amino acid.
Mutations in Junk DNA are not selected.

lactose intolerance in junk??

41
Q

When did life first appear?

A

3.8 billion years ago.

42
Q

How did life probably begin?

A

As RNA molecules to encode information.

43
Q

How would RNA exist without cells?

A

Protobionts made out of lipids occur spontaneously, and RNA can reproduce within them.

44
Q

How old is the earth?

A

4.5 billion years old.

45
Q

When did the cambrian explosion happen and what is it?

A

540-515 Million years ago?

Most of the animals we now see appeared.

46
Q

Why did the cambrian explosion happen?

A

Physiological change - dissolved oxygen levels allow active life style.

Geographical change - new sea/niche

Geochemical change - sea-level changes leads to abundance of trace metals to make exoskeletons.

Biological change - increase in zooplankton allows new predators to arise, thus increasing selection pressure.

47
Q

What happened at the end of the Permian?

A

250 m years ago, mass extinction. caused by volanoes, tectonic movement, possibly asteroids.
Allowed for expansion of diapsids (became dinosaurs) and therapsids (our ancestors) survived.

48
Q

How can a species appear?

A

Time.
Isolation.
Selection.

49
Q

Describe polyploidy speciation.

A

Type of sympatric speciation. Failed meiosis gives a plant polyploidy - more than 2 homo chromosomes. Plants can self pollinate but not mate with normal plants, if numerous plants end up with the same no of chromosomes they can reproduce and form a new species.

50
Q

Describe hybrid zones.

A

2 seperate populations meet and mate.

Allele frequencies change across the zone, suggesting an obstacle to gene flow.

51
Q

What is hymenoptera?

A

wasps,ants and bees.

Large order of insects.

52
Q

Are we still evolving?

A

weight up, height and first child down, menopause older.
But hard to distinguish between environment and genes.

EPAS1 gene - controls rbc production, mutation in Tibetans who live in 40% less oxygen.

53
Q

Where do we come from?

A

All from africa.

54
Q

How are we related to Neanderthols?

A

Cousins, not ancesters.

55
Q

What are the Denisovans?

A

More closely related to the Neanderthals, the Tibetans got their EPAS1 allele from them.

56
Q

What is macroevolution?

A

Evolution on a big scale, the evolution events above the level of the species - ie of major groups such as mammals, reptiles.

57
Q

What is microevolution?

A

Changes in the gene pool of an organism over time.

evolutionary events within a species or population..

58
Q

How do microevolution and macroevolution relate?

A

Microevolution gives rise to macroevolution.

59
Q

What is the gene pool?

A

all alleles of all genes of all individuals in a population.

represents all of the genetic variation of the raw material of evolution.

60
Q

What do you need for natural selection to occur?

A

Differential reproductive success, and genetic variation.

61
Q

What is population genetics?

A

the study of microevolution.

synthesis of darwin and mendel.

62
Q

What can population genetics tell us?

A

Whether a population is responding to natural selection.
Bacteria - antibiotic resistance.
Viruses - resistance to antiviral drugs.

63
Q

What is Conservation genetics?

A

Conserving and restoring biodiversity

64
Q

What is the Hardy Weinberg equilibrium?

A

p^2 + 2pq + q^2 = 1

RR Rr rr

65
Q

What happens when Hardy Weinberg equilibrium is reached?

A

allele and genotype frequencies remain unchanged.

66
Q

When can the Hardy Weinberg equilbirium be applied?

A

Large population.
Random mating.
No migrating.
No selection.

67
Q

Describe the allele for alcohol dehydrogenase.

A

This ADH allele has been selected following the domestication of rice ~10,000 YBP.

68
Q

What is clinal variation?

A

Gradual change in phenotype across a geographic gradient.

69
Q

What are effects of low genetic diversity?

A

high susceptibility to infection.
low sperm count.
high infant mortality.

cheetas

70
Q

Define sexual conflict theory - cheetas.

A

males mate with as many females as possible, no paternal care.
females desire to mate with the fittest male - conflicting desires.

71
Q

What is polyandry?

A

Mating where the females mate with more than one male. Cheetas, offspring have high variability, can survive pathogens.

72
Q

What is polygyny?

A

Where a male mates with more than one female. Lions and leapards.

Genes, evolution & development (5 decks)

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